Making and breaking test of dead-tank type GCB rated on ...€¦ · - 2-break dead-tank type -...

Making and breaking test of deadMaking and breaking test of dead -- tank type GCB tank type GCB rated on 800kV 50kArated on 800kV 50kA

IEEE-PES Switchgear Committee

High Power Testing DepartmentHigh Power Testing Department--II

Introduction

Breaker rating and type- 800kV, 50kA, 50Hz for GIS- 2-break dead-tank type- kpp(1st-pole-to clear factor) =1.3 (Earthed neutral system)- kcc (capacitive voltage factor) = 1.2

Test item and test date (1) Certificate of short-circuit making and breaking performance

Test item : STC, BTF, SLF, OPDate : September 2005 to February 2006

(2) Certificate of capacitive current switching performanceTest item : Line charging current switching Date : June 2006 to July 2006


Introduction

- MC : Main Contact- CCR : Contact for Closing Resistor- R : Closing Resistor- OM : Operating Mechanism- C : Grading Capacitor

Dead-tank circuit breaker


Introduction

Purpose of test

(1) Evaluate making and breaking performance between contacts (Short-circuit current, capacitive current)

(2) For dead-tank breaker, evaluate insulation performance of phase-to-enclosure in a condition of hot-gas during short-circuit currentinterruption

(3) For dead-tank breaker, evaluate insulation performance of phase-to-enclosure in a condition of capacitive current switching


Reference standard(1) IEC 62271-100 (2003)

High-voltage switchgear and controlgear –Part 100: High-voltage alternating-current circuit-breakers

(*) General for circuit breaker testing

(2) IEC 61633(1995)High-voltage alternating current circuit-breakers –Guide for short-circuit and switching test procedures for metal enclosed and dead-tank circuit-breakers(*)Special requirement for dead-tank circuit breaker

Test requirement for short-circuit current


Basic requirements for unit testing

(1) For verifying the performance against mechanical stress of the arcenergy by the short-circuit current interruption, current should beinterrupted by full-unit

(2) For verifying the interrupting performance between contacts, TRV/RV corresponding with number of unit shall be applied

(3) It is necessary to verify the dielectric performance for phase-to-enclosure of dead-tank type breakerEven if unit-test, full-voltage should be applied phase-to-enclosure

Test requirements for short-circuit current (IEC)


Interrupting phenomena for short-circuit current

High current interval (t0 ~ t1)- High arc energy- Electromagnetic force

Interaction interval (t1 ~ t2)- Small post-arc current

High voltage interval (t2 ~)- TRV, RV


Basic requirements (1) It is necessary to verify the dielectric performance for

phase-to-enclosure of dead-tank type breaker

(2) Initial voltage jump should be limited for appropriate evaluation of interrupting performance

Test requirements for capacitive current (IEC standard)


Interrupting phenomena for capacitive current

Next page


Interrupting phenomena for capacitive current

Initial voltage jump (u1, t1)

t2(ms)

U1(PU) t1

≤0.05×kaf

≤0.02×kaf

7.3ms(60Hz)

≥1.95100%2

8.7ms(50Hz)≥ t1

or t3(#)

≥1.9810~30%1

Uc(PU)

TRV

ItTest Duty

1pu : Peak of power frequency test voltage

(#) : t1 or t3 of T100s


4-parameter TRV of KERI

Circuit for generating double frequency TRVCircuit-1 : High-frequency circuit for U1, t1Circuit-2 : Low-frequency circuit for UC, t2

HF TRV

LF TRV

G : Spark-gap switch


Type-1* Dead-tank breaker* Designed with 2-break unit and single-operating mechanism

Circuit breaker for test

Interrupting unit

Operating mechanism


Type-2* Dead-tank breaker* Designed with 2-break unit and two separated operating mechanism

Circuit breaker for test

Interrupting unit

Operating mechanism


Test method for each test duty

T100s(a) Half-pole synthetic making test by step-up transformer method

T100s(b), T100a Full-pole voltage injection test to verify full-insulation of phase-to-enclosure to fulfill IEC requirements

T10, T30, T60, OP Half-pole voltage injection method to increase the test efficiency

SLF (L90, L75) Half-pole current injection method to evaluate thermal failure


Short-circuit Generator

Short-circuitTransformer

Synthetic making facilities Synthetic breaking facilities

Synthetictest cell

KERI Testing facilities


Synthetic making test facilities

HCS : High-speed Closing Switch- Maximum operating voltage (UOV(max)) : 350kVac- Minimum Triggered operating voltage (UTOV(min)) : 10kVp Current / duration : 63kA/60ms

ITMC : Initial Transient Making current circuit - R-C series

UP TR : Step-up transformer - Capacity (Pn) : 2.6MVA- Primary voltage : 13.5kV, 24kV- Secondary voltage : 50kV ~ 350kV- impedance : %Z=12.2%, X=5.88kΩ, R=0.89kΩ


Synthetic making test

Vc : Current source voltageVt : Test voltage

Bt : Test breakerIt : Test current

Ba2 : Auxiliary breakerBa1 : Auxiliary breaker


Unit test method (IEC 61633 requirements)

Across contact : Voltage considering the voltage distributionfactor between units is applied on unit (V+)

Phase-to-enclosure : Full voltage (V+ - VE)Full-voltage is applied to center-part of circuit breakerActual service condition : Full-voltage is applied on one of

outer part


Full-pole breaking test (KERI method)

Voltage injection synthetic testTest breaker was floated and insulated from earth on supporting structureEnclosure and one bushing were short-circuitedT00s(b) and T100a have been performed by using full-pole testing method to verify the dielectric performance

Full-voltage

0


Full-pole breaking test

Voltage application : Two divided voltage source o 50% of total voltage (V+) applied to supply side bushing ()o 50% of total voltage (V-) applied to floated enclosure and

load side bushing ()o Full voltage (Vt = V+ - V-) applied to

* Across contacts : Verification of interrupting performance* Phase-to-enclosure : Verification of dielectric performance

Full-voltage


About control and measurement* Under the high-potential (50% of TRVp, 600kVp)o Control of circuit breaker operation should be performedo Operating signal should be measured to verify the breaker

performanceo Therefore, optical signalization is necessary for test



Optical system for test- Battery for breaker operation : Installed on the insulated

supporting structure - Optical operation control : Sequence timer - Optical measuring signal : Closing / Opening signal

Stroke curve




Test result


What are the advantages of this method?

o Full-voltage can be applied to contacts

o Full-voltage is applied to the side that hot gas is emitted

during interrupting process (equivalent with service condition)

o Insulation stress of testing facilities is reduced to half of test rating

What are the disadvantages of this method?

o Insulated supporting structure

o Difficulty in operation/control and measurement



Capacitive current switching test

Test method- Power frequency current injection method by using

L-C oscillating circuit- Between contact : Half-pole testPhase-to-enclosure : Full-voltage

Purpose of test - Verification of re-strike between contacts - Full-pole voltage on phase-to-enclosure- Minimized voltage jump(u1, t1) to fulfill requirements specified in IEC 62271-100



Test rating for half-pole unit testing

- Test voltage : (800/ √3 )*kc*kd=305kVrms

- Test current : LC2-900A, LC1-270A

Kc: Capacitive voltage factor(1.2: line charging current

switching for earthed-neutral system)

Kd: voltage distribution factor for half-pole unit testing (0.55)



Voltage application - DC and AC recovery voltages were superimposed to one terminal

(*) Across contacts : Half-pole test voltage(*) Phase-to-enclosure : Full voltage

Even if half-pole testing, full voltage was applied on phase-to-enclosure : (800/ √3 )* √2 *kc=784kV



Refer to next page



No voltage jump ; No initial voltage



What are the the advantages of this method

- Verification of full insulation on phase-to-enclosure

- No initial voltage jump(U1, t1)

- Increase the testing capacity



What are the disadvantages of this method

- Over charging due to the voltage decay(Approximately 15-20% at 75ms(time constant) of LPF)

- Impossible to maintain the power frequency oscillating voltage during 0.3s (Needed additional voltage test)

- Frequency difference between injected current (iv(t))and recovery voltage (v(t))


Photographs after test


Conclusion

Type-test for full-insulation performance has successfully been completed- Short-circuit performance - Capacitive current switching performance

Next challenge- Full insulation test of 1100kV circuit breaker


Thank you!!Park, Seung JaeE-mail : [email protected] : 82-(0)55-280-1525Fax : 82-(0)55-280-1596

Making and breaking test of dead-tank type GCB rated on ...€¦ · - 2-break dead-tank type -...

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